*2.4.3 Side effect of acaricides on phytoseiid mites with an emphasis on* Phytoseius plumifer

Use of pesticides cannot be eliminated in a short period of time in perennial crops because phytoseiid mites, as the most important predators of phytophagous mites, might not be able to maintain the spider mite populations below the

**Figure 2.** *The age specific survival (lx) and age-specific fecundity (mx) (*♀*/*♀*) of* Phytoseius plumifer *on corn pollen.*

economically acceptable level on their own. Therefore successful utilization of biological control agents could depend on the compatibility of the natural predators with pesticides [35]. Most of the phytoseiid mites that naturally occur on plants, even in the absence of tetranychids, are generalist predators [36] and must be preserved using selective plant protection products [37]. Studying the side-effects of pesticides on natural enemies, including predaceous mites is an important task in pest management program, however, the use of pesticides remains necessary due to inadequate control achieved by natural enemies. The combination of biological and chemical control as an IPM program is only possible when the side-effects of pesticides on natural agents are well known [38].

Any indirect effects, which are referred to as sublethal, latent, or cumulative adverse effects may be associated with inhibiting longevity, fecundity, reproduction (based on the eggs laid by females), development time, mobility, prey consumption, emergence rates, and sex ratio and effects of sublethal concentration on the subsequent generation. In our previous study, the subletal effects of two acaricides abamectin (Vermectin\_ 1.8% EC, Giah, Iran) and fenpyroximate (Ortus 5% SC, Giah, Iran) on the predatory mite *P. plumifer* fed on *T. urticae* was assessed in laboratory conditions. The adult predators were exposed to the residues of these acaricides on fig leaves for LC50 value determination based on a concentration–response analysis. Then sublethal effects of acaricides on performance of treated females and their offspring of *P. plumifer* were assessed.

#### *2.4.3.1 Materials and methods*

The *P. plumifer* individuals were originally collected from unsprayed (for ten years) fig orchards of Iran. The rearing method were explained comprehensively [34, 39]. All laid eggs were transferred daily from rearing arena to new arenas and were reared to adulthood and then used in the bioassay experiments. Pollen grains and *T. urticae* were used as food source in rearing and treatment arena.

#### *2.4.3.1.1 Concentration-response bioassay*

Concentration–response bioassay was carried out for acaricides using adult females and males at the first day of emergence. A modification of the leaf-dip technique was used [34, 39]. The sublethal concentrations consisted of LC10, LC20 and LC30 were evaluated and used for assessment of sublethal effects on biological performance of *P. plumifer* [34, 39, 40].
